Light Health Dictionary

Pupillary constriction in the EYE in response to light. The direct light re?ex involves pupillary constriction in the eye into which a light is shone; the consensual light re?ex is the pupillary constriction that occurs in the other eye. The a?erent or inward pathway of the re?ex is via the optic nerve, and the e?erent or outward pathway is via the occulomotor nerve.... light reflex

A mechanical trap which use a combination of light and/or carbon dioxide to attract and trap adult mosquitoes, e.g. Centres for Disease Control and Prevention (CDC) Light Trap.... light traps

Invisible light from the part of the electromagnetic spectrum immediately beyond the violet end of the visible light spectrum. Long wavelength ultraviolet light is termed , intermediate , and short.

Ultraviolet light occurs in sunlight, but much of it is absorbed by the ozone layer. The ultraviolet light (mainly ) that reaches the earth’s surface causes the tanning effects of sunlight and the production of vitamin D in the skin. It can have harmful effects, such as skin cancer (see sunlight, adverse effects of).

Ultraviolet light is sometimes used in phototherapy.

A mercury-vapour lamp (Wood’s light) can also produce ultraviolet light.

This is used to diagnose skin conditions such as tinea because it causes the infected area to fluoresce.... ultraviolet light

reflex changes in the eye to enable vision either in normal light after being in darkness or in very bright light after being in normal light. The pupil contracts (see pupillary reflex) and the pigment in the *rods is bleached. Compare dark adaptation.... light adaptation

n. the sensation experienced, usually after the 36th week of gestation, by many pregnant women, particularly those carrying their first child, as the presenting part of the fetus enters the pelvis. This reduces the pressure on the diaphragm and the woman notices that it is easier to breathe. Compare engagement.... lightening

see pupillary reflex.... light reflex

see photodermatosis.... polymorphous light eruption

ultraviolet light filtered through a nickel oxide prism, which causes fluorescence in skin and hair affected by some fungal and bacterial infections and is therefore useful in diagnosis. For example, *erythrasma fluoresces coral pink, while scalp ringworm caused by Microsporum species fluoresces green. [R. W. Wood (1868–1955), US physician]... wood’s light